Design of a PWM-type Bipolar Pulse Generator with High Dv/dt Output

With the development of voltage Silicon Carbide (SiC) devices, motor windings and power inverters tend to encounter pulse width modulation (PWM) pulses with higher dv/dt. However, existing pulse generators for partial discharge testing cannot generate ultrahigh dv/dt with nanosecond rising time to emulate the rising edge of the PWM from SiC based converters. To address this problem, a new PWM-type pulse generator with ultra-high dv/dt output is designed. The generator can generate bipolar outputs at ± 1.2kV with a slew rate of $\pm 50kV/\mu s$ and unit polar output waveform at 1.2 kV with a slew rate of 250 kV$/\mu s$. The width and frequency of the bipolar PWM-type pulses can be accurately controlled. The overall volume of the generator is only 55 $in^{3}$. The detailed description of the circuit, its operation modes and the method to adjust and optimize the output voltage's dv/dt are presented in this paper.